'79 Scorpion whip 440 questions - Page 3 - Snowmobile Forum: Your #1 Snowmobile Forum

ponchonutty · 08-25-2008, 10:16 PM

Well, I've been busy with other things lately. This sled has been bothering me though why it ran great the first time I started it. I then noticed the carb leaking gas so I got a carb kit. Started it again which was harder to start but it ran real rough and hasn't started since. So, I'd like to go through the carb once again. RJ or anyone, is there any literature that can be found on how to rebuild these carbs or how to tune them? I think I want to try here first then maybe mess with trying to rig something so I can read manifold pressures and such. Any help is greatly appreciated.

**RJ Gleason** · 08-26-2008, 08:10 AM

remind me again, the carb make and model.
I have a manual that has the specifics for most carbs and can scan and post the pages for you.

ponchonutty · 08-26-2008, 09:29 PM

I'll have to look at the model. It's a Walbro and it's on a '79 440 Whip

ponchonutty · 09-03-2008, 08:19 PM

WF31 is what I saw on the side of the carb. RJ, is that what you were asking?

**RJ Gleason** · 09-04-2008, 07:32 AM

Yep, wf is the carb model and If I am correct it is a float carb?
I will check when I get home to be sure.

ponchonutty · 09-04-2008, 08:18 AM

Yep, it has a float.

ponchonutty · 09-05-2008, 04:05 PM

RJ, did you find anything yet? Also, I think I found a Mikuni carb that would work but the mounting flange is different than what the Walbro carb has. Would I need to change the intake on the Cuyuna or is there something else I could use if I end up trying to use a different carb?

**RJ Gleason** · 09-05-2008, 09:38 PM

Sorry, been extremely busy and haven't had time. Next week for sure.

ponchonutty · 09-07-2008, 08:52 PM

No problem. Just getting ancy. Didn't matter anyways since I blew out my back. Hopefully next week I'll get on it.

ponchonutty · 09-12-2008, 05:56 PM

UPDATE: Well I was able to score a bunch of parts from a guy I bumped into. He had about 40 sleds of all kinds laying around with 3 Scorpions in the bunch. One was a Sting that was pretty complete so I got the Mikuni carb and some other odds and ends. Bolted the carb up (yeah I know, I didn't open it up or clean it but it looked real clean) and gave it a whirl. I got it to start up but couldn't keep it going and then that was it. Just like before. So, I guess it's time to check the seals.

JheLrey · 09-12-2008, 06:51 PM

Clean the carb!

ponchonutty · 09-13-2008, 08:39 AM

I did what I had to do to make sure the carb was OK. When I mean it was clean I meant it was real clean! I pulled the bottom bowl off and it was very clean inside. The sled won't even pop when you spray starting fluid in it. Like I said before I really am starting to think it's a seal somewhere. I don't think it's the outer seals because the very first time I had it running I sprayed all kinds of carb cleaner on them and it never changed pitch.

One thing I did learn about this motor is supposly the top half of it has been redone a short time ago. I guess the previous owner was having issues so he and a buddy do some work on it. They then ran into a problem trying to get it to restart after running a while so they took it to the shop I bought it from. That shop is the place that stated the center seal being bad. Then the owner decided it wasn't worth hauling home and left it there.

JheLrey · 09-13-2008, 04:28 PM

Well, if the sled will not pop with starter fluid, are you getting spark? If not, it's electrical.

ponchonutty · 09-14-2008, 07:49 PM

Yep. I've always have great spark. Like stated before....If I let it set for a long time, prime it once or twice then pull it it'll fire right up. I'll try to feather the throttle as much as I can but it'll eventually stall out. If I try to restart it again it won't do much at all.

BTW, I got all the pieces to check the case for leaks except intake and exhaust plates. I thought I can just take some pieces of solid rubber and sandwich that inside them to seal them up.

ponchonutty · 09-16-2008, 09:58 PM

Rj, does the Cyuna engine have reeds????

**RJ Gleason** · 09-17-2008, 09:37 AM

Not to my knowledge.

ponchonutty · 09-17-2008, 02:03 PM

I didn't think so. I haven't had the time to tear apart anything as of yet and was just kicking around ideas. I did pull on it today and had it running for about 15 seconds then that was it. I have no idea why I can start it but not keep it running. I've never had this problem before. It seems the more I mess with it, the worse it gets.

ponchonutty · 09-17-2008, 08:25 PM

OK so I played around with it a little. I was able to start it again and found that if I shot some air from my compressor into the carb it'd straighten up a bit. So then I decided to unhook the fuel pump when I got it started again. When the carb would start to run out of fuel it seemed to actually run like it is supposed to. So, does this mean that the carb needs to be rejetted? Or would it mean there's an internal issue where the engine isn't creating enough vacuum or getting enough air? I tried messing with the settings on the Mikuni but it didn't matter. Again, this Mikuni cam straight off of another running Cuyuna 440. I did learn that the previous owner of the sled said that he had done a lot of work on the top end of this motor. Could he have messed something up????

**RJ Gleason** · 09-18-2008, 09:09 AM

Could be jetted too rich, maybe, or the float is not quite high enough or the metering needle is not sealing.
Another thing to try is to move the center needle on the slide up or down one notch to see if it makes a difference.

JheLrey · 09-18-2008, 01:28 PM

From what you stated, sounds like it is flooding itself out. Clean the carbs, adjust them, and start over.